Speaker



NOV; 21, 1939. SERGE 2,180,615

SPEAKER Filed May '7, 1937 INVENT OR.

25 B. fierge Patented Nov. 21, 1939 UNITED STATES PATENT OFFICE 6 Claims.

My invention pertains to a transducer and more particularly to a speaker of the type embodying a magnetic circuit including a yoke, a

pole plate and pole stem, and a central permanent magnet slug, preferably located in the center of -the yoke and axially aligned with the inner pole piece.

An object of my invention is to provide an improved magnetic circuit by providing a simplified structure which can be very readily assembled and positioned in said circuit for obtaining a maximum of performance.

Another object of my present invention is to provide for improved assembly by incorporating in the magnetic circuit a permanent magnet constructed to facilitate this assembly.

Other objects of my invention are to provide a more economical speaker construction by incorporating various improved structural details which facilitate assembly and provide for most economical manufacture.

For a more detailed understanding of my invention, reference may be had to the accompanying drawing which illustrates one form which my invention may assume, and in which:

Fig. 1 is a view of a speaker showing a portion thereof in side elevation and having portions thereof shown in section to illustrate the magnetic circuit incorporated in the device.

Fig. 2 is a sectional view taken on the line 22 of Fig. 1,

Fig. 3 is a fragmentary detail perspective view of a. portion of the yoke illustrating a simplified manner for providing transformer mounting means, and

Fig. 4 is a distended view in perspective showing that portion of the magnetic circuit comprising the permanent magnet and inner pole stem which parts are fabricated and secured together by a single fastening means.

In the accompanying drawing I have illustrated a speaker A which embodies a cone bracket 10 supporting in the usual way a vibratory cone diaphragm l I, the bracket being secured by suitable fastening means l2 to the pole plate l3 of the magnetic circuit.

This magnetic circuit incorporated in speaker A preferably comprises a yoke 14 associated with said pole plate 13 and carries a permanent magnet IE to which is secured the inner pole piece I6 projecting through an opening I! in the outer pole plate I3 and spaced therefrom to provide a gap l8 in which the vibratory voice coil structure I!) is adapted to operate. This voice coil is preferably supported by the outer flexible diaphragm (c1. lie-117) support 20 and the inner spider support 2|, and a pilot cup 22' is carried by said pole plate l3 to pilot the inner pole stem l6 and definitely locate the same concentrically within the opening I! of said outer pole plate.

The permanent magnet l5 comprises a single slug of permanent magnet material which is constructed with a radially extending slot 2| which extends from the center of said permanent magnet radially to the peripheral edge of said magnet (see Figs. 2 and 4). The outer peripheral side of the magnet is tapered as at 22 to provide a substantially frusto-conical permanent magnet structure and the slot 2| is preferably tapered oppositely to the taper of the outer edge of said magnet as at 23, thereby providing a maximum of contact arrangement for the base of the magnet for operative contact with the yoke M. The pole stem comprises a fabricated structure including a washer 24 and a pole piece 25 and the washer is adapted to be clamped between the pole piece 25 and permanent magnet l5 by means of a screw or other suitable fastening device 26 threaded through an opening in the yoke, through the slot 2| of the magnet and into the tapered hole 21 of said pole piece 25. It will be thus noted that the washer 24 and permanent magnet l5 are both rigidly clamped to the yoke by means of a single screw and the magnet though provided with a slot may be substantially referred to as a single center slug. It will be also noted that the pole face of said magnet contacting with the yoke is of greater area than the pole face contacting with the inner pole piece structure, particularly the pole face formed by the washer 24 and that the axial length of said magnet is substantially less than the mean diameter of said permanent magnet taken in a plane transverse to the axis of said magnet.

It will be further noted that I have provided an economical structure for providing a mounting for the transformer B. This is accomplished by swedging ears 30 from the arm portion 3| of said yoke I4. It will be noted that the swedging ears 30 are formed in such a way as to provide the outer face thereof substantially flush with the outer surface of the yoke arm 3| (see Fig. 1), the transformer being provided with the ears 32 which seat against the ears 30 and adapted to be secured thereto by means of rivets or other fastening devices 33.

It will be noted that the construction provides a very simple and economically manufactured structure which may be quickly assembled together when manufacturing or readily serviced with a minimum of labor and expense. I have provided a novel inner pole stem structure particularly adapted for assembly with a slotted permanent magnet which parts may be economically assembled with a minimum of labor and expense.

Although I have illustrated but one form of my invention and have described in detail but a single application thereof, it will be apparent to those skilled in the art to which my invention pertains that various modifications and changes may be made therein without departing from the spirit of my invention or from the scope of the appended claims.

What I claim as my invention is:

1. A frusto-conical cast permanent magnet having substantially parallel polar plane surfaces and having a radial slot extending from the axis thereof to the outer peripheral surface, said slot being tapered reversely with respect to the taper of said peripheral surfaces of said magnet.

2. A frusto-conical cast permanent magnet having substantially parallel polar plane surfaces and having a radial slot extending from the axis thereof to the outer peripheral surface, the side walls of said slot converging toward the base of said frusto-conical magnet, whereby to provide a maximum of polar plane surface at the base thereof.

3. In a transducer, a sub-assembly of the character described including a yoke, a pole stem and a permanent magnet axially aligned with said pole stem and comprising a slug of material having polar plane surfaces respectively contacting with said yoke and pole stem, said permanent magnet slug having a radial slot extending from the axis to the outer peripheral surface thereof, and a single fastening means extending through said slot substantially coaxial with respect to the magnet and pole stem axes and securing said magnet and pole stem to said yoke.

4. In a transducer, 9. sub-assembly of the character described including a yoke, a pole stem and a permanent magnet axially aligned with said pole stem and comprising a slug of material having polar plane surfaces respectively contacting with said yoke and pole stem, said permanent magnet slug having a radial slot extending from the axis to the outer peripheral surface thereof and from one polar plane surface to the other, and a single fastening means extending through said slot substantially coaxial with respect to the magnet and pole stem axes and securing said magnet and pole stem to said yoke.

5. In a transducer, a sub-assembly of the character described including a yoke, a pole stem and a permanent magnet axially aligned with said pole stem and comprising a slug of material having polar plane surfaces respectively contacting with said yoke and pole stem, said permanent magnet comprising a single slug of material of a frusto-conical shape and arranged for contacti'ng the polar plane surface of greater area with said yoke, and means securing said pole stem and magnet to said yoke.

6. In a transducer, a sub-assembly of the character described including a yoke, a pole stem and a permanent magnet axially aligned with said pole stem and comprising a slug of material having polar plane surfaces respectively contacting with said yoke and pole stem, said permanent magnet comprising a single slug of material of a frusto-conical shape and arranged for contacting the polar plane surface of greater area with said yoke, said permanent magnet further having a radial slot extending from the axis to the outer peripheral surface thereof and from one polar plane surface to the other, and a single fastening means extending through said slot substantially coaxial with respect to the magnet and pole stem. axes and securing said magnet and pole stem to said yoke.

IGOR B. SERGE. 

